Composition for forming anti-reflective coating for use in lithography

ABSTRACT

A composition for forming anti-reflective coating for use in a lithographic process in manufacture of a semiconductor device, comprising as a component a resin containing cyanuric acid or a derivative thereof, or a resin containing a structural unit derived from cyanuric acid or a derivative thereof. The structural unit is preferably represented by formula (1): 
                         
and can be contained in a main chain or a side chain, or both main chain and side chain of a resin. The anti-reflective coating for lithography obtained from the composition has a high reflection reducing effect and does not cause intermixing with a resist layer to give an excellent resist pattern. It has a higher selectivity in dry-etching compared with the resists.

TECHNICAL FIELD

The present invention relates to a composition for forminganti-reflective coating that is effective in lowering of adverse effectsdue to reflection off an underlying substrate in a lithographic processby using ArF excimer laser; and a method of forming a resist pattern byusing the composition for forming anti-reflective coating.

BACKGROUND ART

Conventionally, in the manufacture of semiconductor devices,micro-processing by lithography using a photoresist composition has beencarried out. The micro-processing is a processing method includingforming a thin film of a photoresist composition on a silicon wafer,irradiating actinic rays such as ultraviolet rays via a mask patterndepicting a pattern for a semiconductor device, developing it to obtaina resist pattern, and etching the silicon wafer using the resist patternas a protective film to form fine concavities and convexitiescorresponding to the pattern on the device. However, recent progress inhigh integration of semiconductor devices, there has been a tendencythat shorter wavelength actinic rays are being used, i.e., ArF excimerlaser beam (193 nm) has been taking the place of KrF excimer laser beam(248 nm). Along with this change, influences of random reflection andstanding wave off a substrate have become serious problems. Accordingly,it has been widely studied to provide an anti-reflective coating betweenthe photoresist and the substrate (Bottom Anti-Reflective Coating,BARC).

As the anti-reflective coating, inorganic anti-reflective coatings madeof titanium, titanium dioxide, titanium nitride, chromium oxide, carbonor α-silicon and organic anti-reflective coatings made of alight-absorbing substance and a high molecular compound are known. Theformer requires an installation such as a vacuum deposition apparatus, aCVD (chemical vapor deposition) apparatus or a sputtering apparatus. Incontrast, the latter is considered advantageous in that it requires nospecial installation so that many studies have been made. For example,mention may be made of the acrylic resin type anti-reflective coatinghaving a hydroxyl group and a light absorbing group in the same moleculeobtained by crosslinking reaction as disclosed in U.S. Pat. No.5,919,599 and the novolak resin type anti-reflective coating having ahydroxyl group and a light absorbing group in the same molecule obtainedby crosslinking reaction as disclosed in U.S. Pat. No. 5,693,691, and soon.

The physical properties required or desired for organic anti-reflectivecoating materials include high absorbance to light and radioactive rays,no intermixing with the resist layer (being insoluble in resistsolvents), no diffusion of low molecular substances from theanti-reflective coating material into the topcoat resist upon coating orheat-drying, and a higher dry etching rate than the resist. They aredescribed in, for example, Proc. SPIE, Vol. 3678, 174-185 (1999) andProc. SPIE, Vol. 2195, 225-229 (1994).

On the other hand, Japanese Patent Laid-open No. 11-279523 describes atechnique in which tris(hydroxyalkyl)isocyanurate substituted with anaromatic compound or an alicyclic compound is used as a UV absorbentcovering a broad spectrum.

DISCLOSURE OF INVENTION

The present invention provides a composition for forming anti-reflectingcoating that prevents effectively reflection particularly when anirradiating light with a wavelength of 193 nm is used formicrofabrication, and that can be rapidly removed in removal processlater, and that leads to a very useful anti-reflecting coating. That is,an object of the present invention is to provide a composition forforming an anti-reflective coating for lithography that has a highreflection-preventive effect, does not cause intermixing with a resistlayer to give an excellent resist pattern and has a higher dry-etchingrate compared with the resist; and a method of forming resist pattern byusing the composition for forming anti-reflective coating.

In a first aspect, the present invention provides a composition forforming anti-reflective coating for use in a lithographic process inmanufacture of a semiconductor device, comprising as a component a resincontaining cyanuric acid or a derivative thereof, or a resin containinga structural unit derived from cyanuric acid or a derivative thereof.

In a second aspect, the present invention provides the composition asdescribed in the first aspect, wherein the component contains cyanuricacid or a derivative thereof, represented by formula (1):

wherein R¹, R² and R³ independently of one another are a hydrogen atom,a halogen atom, a substituted or unsubstituted alkyl group having 1 to10 carbon atoms, a substituted or unsubstituted benzene derivativegroup, a substituted or unsubstituted vinyl derivative group or an epoxyderivative group.

In a third aspect, the present invention provides the composition asdescribed in the first aspect, wherein the component is a resincontaining in a main chain or a side chain the structural unit derivedfrom the compound of formula (1), or a resin containing in both a mainchain and a side chain the structural unit derived from the compound offormula (1).

In a fourth aspect, the present invention provides the composition asdescribed in the second or third aspect, wherein the compound of formula(1) is tris(hydroxyalkyl)isocyanurate.

In a fifth aspect, the present invention provides the composition asdescribed in any one of the first to fourth aspects, further comprisinga crosslinking agent having at least two crosslink-forming functionalgroups.

In a sixth aspect, the present invention provides method of forming ananti-reflective coating for use in a lithographic process in amanufacture of a semiconductor device, comprising the steps of: coatingthe composition as described in any one of the first to fifth aspects ona substrate, and baking it.

In a seventh aspect, the present invention provides a process formanufacturing a semiconductor device comprising the steps of:

-   -   coating the composition according to any one of claims 1 to 5 on        a substrate    -   baking it to form an anti-reflective coating,    -   covering the anti-reflective coating with a photoresist,    -   exposing the substrate covered with the anti-reflective coating        and the photoresist to light,    -   developing the exposed substrate, and    -   transferring an image on the substrate by etching to form an        integrated circuit element.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention relates to a composition for forminganti-reflective coating for use in a lithographic process in themanufacture of a semiconductor device, comprising as a component a resincontaining cyanuric acid or a derivative thereof, or a resin containinga structural unit derived from cyanuric acid or a derivative thereof.

The molecular weight of cyanuric acid or a derivative thereof used inthe present invention ranges from 129 to 1,000, preferably from 129 to600. In addition, the resin containing the structural unit derived fromcyanuric acid or a derivative thereof may vary depending on the coatingsolvents used, the viscosity of the solvent, the shape of the coating,etc., and has a weight average molecular weight of 200 to 1,000,000,preferably 1,000 to 1,000,000.

The composition for forming anti-reflective coating according to thepresent invention contains 0.1 to 50% by weight of solids content. Thecontent of the resin containing cyanuric acid or a derivative thereof,or a structural unit derived therefrom is 0.1 to 50 parts by weight,preferably 1 to 30 parts by weight based on 100 parts by weight of thetotal composition.

Cyanuric acid or a derivative thereof as a component exerts a reflectionreducing effect by absorbing UV light, particularly UV light with awavelength of 193 nm.

As cyanuric acid or a derivative thereof, compounds represented byformula (1) can be used. A composition for forming anti-reflectingcoating can be obtained by mixing a component comprising cyanuric acidor a derivative thereof with a resin and dissolving them in a solvent.In addition, a composition for forming anti-reflecting coating can beobtained by dissolving a resin containing in a main chain or a sidechain the structural unit derived from the compound of formula (1), or aresin containing in both a main chain and a side chain the structuralunit derived from the compound of formula (1) in a solvent.

In the compounds of formula (1), R¹, R² and R³ independently of oneanother are a hydrogen atom, a halogen atom, a substituted orunsubstituted alkyl group having 1 to 10 carbon atoms, a substituted orunsubstituted benzene derivative group, a substituted or unsubstitutedvinyl derivative group or an epoxy derivative group. The halogen atomincludes for example a fluorine atom, a chlorine atom, a bromine atom ora iodine atom. The alkyl group includes for example methyl, ethyl,propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl,n-octyl or n-dodecyl. The benzene derivative group includes for examplephenyl, benzyl, tolyl, methoxyphenyl, xylyl, biphenyl, naphthyl oranthryl. The vinyl derivative group includes for example ethenyl,propenyl, butenyl, butadienyl, hexenyl or octadienyl. The epoxyderivative group includes for example glycidyl or β-methyl-glycidyl.

These alkyl groups, benzene derivative groups and vinyl derivativegroups may be unsubstituted or substituted, and the substituents includefor example a halogen atom such as a chlorine atom, a bromine atom or afluorine atom, a hydroxy group, an alkoxy group or an acyl group.Particularly preferable substituent is an hydroxy group.

The compounds of formula (1) includes tris(hydroxyalkyl)isocyanuraterepresented by formula (2):

compounds represented by formula (3):

and compounds represented by formula (4):

R⁴ and R⁵ in formula (2) are a hydrogen atom, an alkyl group having 1 to12 carbon atoms, or an aromatic group having 6 to 14 carbon atoms suchas phenyl, benzyl or tolyl. Preferable tris(hydroxyalkyl)isocyanurateincludes for example tris(2-hydroxyethyl)isocyanurate,tris(2-hydroxypropyl)isocyanurate, tris(2-hydroxybutyl)isocyanurate ortris(α-methyl-β-hydroxypropyl)isocyanurate.

R⁶ in formulae (3) and (4) is phenyl, benzyl, tolyl, methoxyphenyl,xylyl, biphenyl, naphthyl, anthryl or the like. In addition, x informula (4) ranges from 1 to 1,000. Y and Z in formula (4) is

respectively. The compound of formula (4) can be produced bypolymerizing tris(2,3-epoxypropyl)isocyanurate with phenol as rawmaterials, for example.

As the compound of formula (1), tris(hydroxyalkyl)isocyanuraterepresented by formula (2) is preferably used.

The compound of formula (1) can be used in the form of a mixture with aresin or in the form of a resin to which the compound is chemicallybonded.

In the composition for forming anti-reflective coating according to thepresent invention, in case 1 where a resin is mixed with the compound offormula (1), the compound of formula (1) is bonded to the resin via acrosslinking agent or directly when an anti-reflective coating is formedby applying the composition on a substrate, and drying and baking it.

In the composition for forming anti-reflective coating according to thepresent invention, the compound of formula (1) may be contained in aresin added therein via a chemical bond. In such a case, the resin maycontain a structural unit derived from the compound of formula (1) inits main chain or its side chain connecting to the main chain.

In case 2 where a resin contains a structural unit derived from thecompound of formula (1) in its main chain, the resin is produced bypolymerizing the compound of formula (1) as a monomer via a vinyl groupor an epoxy group thereon. In case 3 where the compound of formula (1)is copolymerized with a monomer polymerizable therewith, the resin maycontain the compound of formula (1) in its main chain.

In case 4 where a resin contains a structural unit derived from thecompound of formula (1) in its side chain connecting to the main chain,the resin is produced by reacting a functional group (e.g., hydroxygroup) on the compound of formula (1) with a functional group (e.g.,hydroxy group or carboxyl group) on the resin to bond the compound offormula (1) with the resin.

Further, cases 1 to 4 may be combined one another.

In the above-mentioned case 2, a resin may be produced by using only thecompound of formula (1). In the above-mentioned cases 1 to 4, the ratioof the compound of formula (1) to a resin can be adjusted to thecompound of formula (1): a resin=1:99 to 99:1 in weight ratio. Thedry-etching rate in anti-reflective coating is improved with an increasein the content of the compound of formula (1).

The resin that is used with the compound of formula (1) in cases 1 to 4preferably has hydroxy group or carboxyl group in order to bind to acrosslinking agent.

The resin may be a homopolymer consisted of a monomer or a copolymerconsisted of a plurality of monomers. The monomer includes thefollowings. Styrenes include for example polyhydroxy styrene, polyα-methyl styrene, poly p-methyl styrene, poly o-methyl styrene, polyp-methoxy styrene, poly p-chlorostyrene or polyvinyl benzoic acid.Acrylic or methacrylic acid or a derivative thereof includes for examplecarboxylic acids such as polyacrylic acid, polymethacrylic acid,polymaleic acid or polyfumaric acid, acrylic acid ester or methacrylicacid ester corresponding thereto, such as poly(methylacrylate),poly(ethylacrylate), poly(propylacrylate), poly(isopropylacrylate),poly(n-butylacrylate), poly(isobutylacrylate), poly(n-hexylacrylate),poly(octylacrylate), poly(2-ethylhexyl-acrylate), poly(laurylacrylate),poly(2-hydroxypropylacrylate) or poly(gycidylacrylate), amide ormethacrylic acid amide, such as polyacrylamide, poly-N-methylolacrylamide or polydiacetone acrylamide, or polyacrylonirile, polyvinylchloride or polyethylvinyl ether. In particular, preferable resins arepolyacrylic 2-hydroxypropyl having hydroxy group and mathacrylatecorresponding thereto, and polyacrylic acid and polymethacrylic acidhaving carboxyl group.

The resin used in the present invention may be any of random copolymers,block copolymers and graft copolymers. The resin for forming theanti-reflective coating of the present invention can be synthesized byvarious methods such as radical polymerization, anionic polymerizationor cationic polymerization. As the type of polymerization, variousmethods such as solution polymerization, suspension polymerization,emulsion polymerization or bulk polymerization are possible.

In the present invention, it is possible to copolymerizenon-crosslinking monomers instead of the above-mentioned resins. Thisallows minute adjustment of dry-etching rate, reflectivity, etc. Such acopolymerizable monomer includes, for example, compounds having at leastone addition polymerizable unsaturated bond selected from acrylic acidesters, acrylamides, methacrylic acid esters, methacrylamides, allylcompounds, vinyl ethers, vinyl esters, styrenes, crotonic acid esters,etc.

The acrylic acid esters include, for example, alkyl acrylates having 1to 10 carbon atoms in the alkyl group.

The methacrylic acid esters include, for example, alkyl methacrylateshaving 1 to 10 carbon atoms in the alkyl group.

Acrylamides include, for example, acrylamide, N-alkylacrylamides,N-arylacrylamides, N,N-dialkylacrylamides, N,N-diarylacrylamides,N-methyl-N-phenylacrylamide, N-hydroxyethyl-N-methylacrylamide,N-2-acetamide ethyl-N-acetylacrylamide, etc.

Methacrylamides include, for example, methacrylamide,N-alkylmethacrylamides, N-arylmethacrylamides,N,N-dialkylmethacrylamides, N,N-diarylmethacrylamides,N-hydroxyethyl-N-methylmethacrylamide, N-methyl-N-phenylmethacrylamide,N-ethyl-N-phenylmethacrylamide, etc.

Vinyl ethers include, for example, alkyl vinyl ethers, vinyl arylethers, etc.

Vinyl esters include, for example, vinyl butyrate, vinyl isobutyrate,vinyl trimethylacetate, etc.

Styrenes include, for example, styrene, alkylstyrenes, alkoxystyrenes,halogenostyrenes, hydroxystyrene, carboxystyrene, etc.

Crotonic acid esters include, for example, alkyl crotonates such asbutyl crotonate, hexyl crotonate, glycerine monocrotonate, etc.

Also, mention may be made of dialkyl itaconates, monoalkyl esters ordialkyl esters of maleic acid or fumaric acid, crotonic acid, itaconicacid, maleic anhydride, maleimide, acrylonitrile, methacrylonitrile,maleylonitrile, etc. In addition, generally, addition polymerizableunsaturated compounds which can copolymerize with the compounds offormula (1) as described above or resins to which the compounds arebonded may be used.

The anti-reflective coating forming composition of the present inventionmay contain a crosslinking agent having at least two crosslink-formingfunctional groups. The crosslinking agent includes, for example,melamines, substituted ureas, polymers having epoxy groups and the like.The agent is preferably methoxymethylated glycoluryl, methoxymethylatedmelamine or the like, more preferably tetramethoxymethyl glycoluryl orhexamethoxymethyl melamine. The addition amount of the crosslinkingagent may vary depending on the coating solvents used, the underlyingsubstrate used, the viscosity of the solvent required, the shape of thecoating required, etc., and usually 0.001 to 20 parts by weight,preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5.0 partsby weight based on 100 parts by weight of the total composition.

The anti-reflective coating forming composition of the present inventionmay contain further light absorbing agents, rheology controlling agents,adhesion auxiliaries, surfactants, etc. in addition to the abovedescribed ones, if necessary.

The rheology controlling agents are added mainly aiming at increasingthe flowability of the anti-reflective coating forming composition andin particular in the baking step, increasing filling property of theanti-reflective coating forming composition into the inside of holes.Specific examples thereof include phthalic acid derivatives such asdimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dihexylphthalate or butyl isodecyl phthalate; adipic acid derivatives such asdi-n-butyl adipate, diisobutyl adipate, diisooctyl adipate or octyldecyladipate; maleic acid derivatives such as di-n-butyl maleate, diethylmaleate or dinonyl maleate; oleic acid derivatives such as methyloleate, butyl oleate or tetrahydrofurfuryl oleate; or stearic acidderivatives such as n-butyl stearate or glyceryl stearate. The rheologycontrolling agents are blended in proportions of usually less than 30parts by weight based on 100 parts by weight of the total composition.

The adhesion auxiliaries are added mainly for the purpose of increasingthe adhesion between the substrate or resist and the anti-reflectivecoating forming composition, in particular preventing the detachment ofthe resist in development. Specific examples thereof includechlorosilanes such as trimethylchlorosilane, dimethylvinylchlorosilane,methyldiphenylchlorosilane or chloromethyldimethyl-chlorosilane;alkoxysilanes such as trimethylmethoxysilane, dimethyldiethoxysilane,methyldimethoxysilane, dimethylvinylethoxysilane,diphenyldimethoxysilane or phenyltriethoxysilane; silazanes such ashexamethyldisilazane, N,N′-bis(trimethylsilyl)urea,dimethyltrimethylsilylamine or trimethylsilylimidazole; silanes such asvinyltrichlorosilane, γ-chloropropyltrimethoxysilane,γ-aminopropyltriethoxy-silane or γ-glycidoxypropyltrimethoxysilane;heterocyclic compounds such as benzotriazole, benzimidazole, indazole,imidazole, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole,2-mercaptobenzoxazole, urazole, thiouracyl, mercaptoimidazole ormercaptopyrimidine; ureas such as 1,1-dimethylurea or 1,3-dimethylurea,or thiourea compounds. The adhesion auxiriaries are added in proportionsof usually less than 5 parts by weight, preferably less than 2 parts byweight, based on 100 parts by weight of the total composition.

The anti-reflective coating forming composition of the present inventionmay contain surfactants with view to preventing the occurrence ofpinholes or striations and further increasing coatability not to causesurface unevenness. As the surfactants, mention may be made of, forexample, nonionic surfactants such as polyoxyethylene alkyl ethers,e.g., polyoxyethylene lauryl ether, polyoxyethylene stearyl ether,polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, etc.,polyoxyethylene alkyl allyl ethers, e.g., polyoxyethylene octyl phenolether, polyoxyethylene nonyl phenol ether;polyoxyethylene/polyoxypropylene block copolymers, etc., sorbitan fattyacid esters, e.g., sorbitan monolaurate, sorbitan monopalmitate,sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitantristearate, etc., polyoxyethylene sorbitan fatty acid esters, e.g.,polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitanmonopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylenesorbitan trioleate, polyoxyethylene sorbitan tristearate, etc.; fluorinebased surfactants, e.g., EFTOP EF301, EF303, EF352 (Tochem Products Co.,Ltd.), MEGAFAC F171, F173 (DAINIPPON INK AND CHEMICALS, INC.), FLUORADFC430, FC431 (SUMITOMO 3M LIMITED), ASAHI GUARD AG710, SURFLON S-382,SC101, SC102, SC103, SC104, SC105, SC106 (ASAHI GLASS CO., LTD.),organosiloxane polymer KP341 (SHINETSU CHEMICAL CO., LTD.), etc. Theblending amount of the surfactants is usually 0.2 parts by weight orless, preferably 0.1 part by weight or less, based on 100 parts byweight of the total composition of the present invention. Thesurfactants may be added singly or two or more of them may be added incombination.

In the present invention, as the solvents for dissolving theabove-described resin, use may be made of ethylene glycol monomethylether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethylcellosolve acetate, diethylene glycol monomethyl ether, diethyleneglycol monoethyl ether, propylene glycol, propylene glycol monomethylether, propylene glycol monomethyl ether acetate, propylene glycolpropyl ether acetate, toluene, xylene, methyl ethyl ketone,cyclopentanone, cyclohexanone, ethyl 2-hydroxypropionate, ethyl2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate,methyl 2-hydroxy-3-methylbutanoate, methyl 3-methoxypropionate, ethyl3-methoxypropionate, ethyl 3-ethoxypropionate, methyl3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate,butyl acetate, ethyl lactate, butyl lactate, cyclohexanone, etc. Theorganic solvents may be used singly or in combination of two or more ofthem.

Further, high boiling solvents such as propylene glycol monobutyl etheror propylene glycol monobutyl ether acetate may be mixed.

Among the solvents, propylene glycol monomethyl ether, propylene glycolmonomethyl ether acetate, ethyl lactate, butyl lactate, andcyclohexanone are preferred for increasing the leveling property.

As the resist to be coated as an upper layer of the anti-reflectivecoating formed by using the composition of the prsent invention, any ofnegative type and positive type resists may be used and such a resistincludes a positive type resist consisting of a novolak resin and1,2-naphthoquinone diazide sulfonic acid ester, a chemically-amplifiedtype resist which consists of a photo acid generator and a binder havinga group which is decomposed with an acid and increases alkalidissolution speed, a chemically-amplified type resist consisting of analkali-soluble binder, a photo acid generator, and a low molecularcompound which is decomposed with an acid and increases the alkalidissolution speed of the resist, a chemically-amplified resistconsisting of a photo acid generator, a binder having a group which isdecomposed with an acid and increases the alkali dissolution speed, anda low molecular compound which is decomposed with an acid and increasesthe alkali dissolution speed of the resist.

As the developer for the above-mentioned positive type photoresist, usemay be made of aqueous solutions of alkalis, e.g., inorganic alkalissuch as sodium hydroxide, potassium hydroxide, sodium carbonate, sodiumsilicate, sodium metasilicate or aqueous ammonia, primary amines such asethylamine or n-propylamine, secondary amines such as diethylamine ordi-n-butylamine, tertiary amines such as triethylamine ormethyldiethylamine, alcohol amines such as dimethylethanolamine ortriethanolamine, quaternary ammonium salts such as tetramethylammoniumhydroxide, tetraethylammonium hydroxide or choline, cyclic amines suchas pyrrole or piperidine, etc. Furthermore, a suitable amount of analcohol such as isopropyl alcohol or nonionic surfactant can be added tothe aqueous solution of above-described alkalis. Among these, apreferred developer includes quaternary ammonium salts, more preferablytetramethylammonium hydroxide and choline.

Now, the method for forming resist patterns by using the composition forforming anti-reflective coating of the present invention will bedescribed. On a substrate for use in the production of precisionintegrated circuit element (for example, transparent substrates such assilicon/silicon dioxide coat, glass substrate or ITO substrate), ananti-reflective coating forming composition is coated by a suitablecoating method, for example, with a spinner, a coater or the like, andthereafter the substrate is baked to cure the composition to fabricatean anti-reflective coating. The film thickness of the anti-reflectivecoating is preferably 0.01 to 3.0 μm. The conditions of baking after thecoating are 80 to 250° C. for 1 to 120 minutes. Then, a photoresist iscoated, it is exposed to light through a predetermined mask, developed,rinsed and dried to obtain a good resist. If necessary, post exposurebake (PEB) may be performed.

EXAMPLES

Hereinafter, the present invention will be described based on examplesbut the present invention is not limited thereto.

Synthesis Example 1 (Synthesis of Resin)

After 90 g of 2-hydroxypropyl methacrylate was dissolved in 455 g ofpropylene glycol monomethyl ether, the reaction solution was warmed at70° C. and simultaneously nitrogen gas was passed into the reactionsolution. Thereafter, 0.9 g of azobisisobutyronitrile (manufactured byJUNSEI CHEMICAL CO., LTD.) was added as polymerization initiator andstirred under nitrogen atmosphere for 24 hours, and then 0.1 g of4-methoxyphenol (manufactured by TOKYO KASEI KOGYO CO., LTD.) was addedas polymerization terminator. The resulting resin was subjected to GPCanalysis and as a result, its weight average molecular weight was foundto be 71,300 in terms of standard polystyrene. The solids content in thesolution was 20%.

Synthesis Example 2

Cresol novolak resin (manufactured by ASAHI CIBA CO., LTD., trade nameECN1299, weight average molecular weight: 3,900, the structure beingshown by formula (5)) was provided.

10 g of cresol novolak resin described above was added in 80 g ofpropylene glycol monomethyl ether and dissolved therein. To thesolution, 9.7 g of 9-anthracenecarboxylic acid and 0.26 g ofbenzyltriethylammonium chloride were added. The resulting mixture wasreacted at 105° C. for 24 hours. GPC analysis of the resulting polymerresin gave a weight average molecular weight of 5,600 in terms ofstandard polystyrene. The chemical structure of the resin is shown byformula (6).

Synthesis Example 3

Tris-(2,3-epoxypropyl)-isocyanurate (manufactured by NISSAN CHEMICALINDUSTRIES, LTD., trade name TEPIC, the structure being shown by formula(7)) was provided.

3.0 g of the above-mentioned tris-(2,3-epoxypropyl)-isocyanurate wasadded and dissolved in 7.0 g of xylene. Then 2.8 g of phenol and 0.17 gof benzyl triethyl ammonium chloride were added to the dissolvedsolution, and thereafter reacted at 140° C. for 24 hours. After thereaction was completed, the reaction solution was gradually cooled,crystals separated out were filtered, and then purified byrecrystalization from a mixed solvent of isopropylalcohol/acetone=9/1.The chemical structure of the resulting compound is shown by formula(8).

Synthesis Example 4

10.0 g of tris-(2,3-epoxypropyl)-isocyanurate was added and dissolved to24.0 g of xylene. After adding 3.2 g of phenol and 0.57 g of benzyltriethyl ammonium chloride to the dissolved solution, reaction wascarried out at 140° C. for 24 hours. After the reaction was completed,the reaction solution was gradually cooled, polymers separated out werefiltered, washed with xylene and dried. The chemical structure of theresulting polymer compound is shown by formula (9). The polymer has aweight average molecular weight of 3,000.

Synthesis Example 5

Tris(2-hydroxyethyl)isocyanurate (manufactured by NISSAN CHEMICALINDUSTRIES, LTD., trade name TANAC, the structure being shown by formula(10)) was provided.

Example 1

0.4 g of tris(2-hydroxyethyl)isocyanurate, 6 g of a reaction solutioncontaining 1.2 g of poly2-hydroxypropylmethacrylate obtained inSynthesis Example 1, 0.4 g of hexamethoxymethylmelamine as acrosslinking agent, and 0.04 g of p-toluenesulfonic acid as a hardeningagent were mixed, and to the mixture 30 g of propylene glycol monomethylether was added as a solvent. Then, the solution was filtered through amicro filter made of polyethylene having a pore diameter of 0.10 μm, andthen, the solution was filtered through a micro filter having a porediameter of 0.05 μm, to prepare an anti-reflective coating compositionin the state of solution. The solution was coated on a silicon waferusing a spinner and the wafer was heated at 205° C. for 1 minute on ahot plate to form an anti-reflective coating (film thickness: 0.08 μm).Measurement of the anti-reflective coating by a spectral ellipsometerindicated a refractive index n of 1.76 and optical extinctioncoefficient k of 0.11 at 193 nm.

Example 2

0.8 g of tris(2-hydroxyethyl)isocyanurate, 4 g of a reaction solutioncontaining 0.8 g of poly2-hydroxypropylmethacrylate obtained inSynthesis Example 1, 0.4 g of hexamethoxymethylmelamine as acrosslinking agent, and 0.04 g of p-toluenesulfonic acid as a hardeningagent were mixed, and to the mixture 30 g of propylene glycol monomethylether was added as a solvent. Then, the solution was filtered through amicro filter made of polyethylene having a pore diameter of 0.10 μm, andthen, the solution was filtered through a micro filter having a porediameter of 0.05 μm, to prepare an anti-reflective coating compositionin the state of solution. The solution was coated on a silicon waferusing a spinner and the wafer was heated at 205° C. for 1 minute on ahot plate to form an anti-reflective coating (film thickness: 0.08 μm).Measurement of the anti-reflective coating by a spectral ellipsometerindicated a refractive index n of 1.76 and optical extinctioncoefficient k of 0.17 at 193 nm.

Example 3

1.2 g of tris(2-hydroxyethyl)isocyanurate, 2 g of a reaction solutioncontaining 0.4 g of poly2-hydroxypropylmethacrylate obtained inSynthesis Example 1, 0.4 g of hexamethoxymethylmelamine as acrosslinking agent, and 0.04 g of p-toluenesulfonic acid as a hardeningagent were mixed, and to the mixture 30 g of propylene glycol monomethylether was added as a solvent. Then, the solution was filtered through amicro filter made of polyethylene having a pore diameter of 0.10 μm, andthen, the solution was filtered through a micro filter having a porediameter of 0.05 μm, to prepare an anti-reflective coating compositionin the state of solution. The solution was coated on a silicon waferusing a spinner and the wafer was heated at 205° C. for 1 minute on ahot plate to form an anti-reflective coating (film thickness: 0.08 μm).Measurement of the anti-reflective coating by a spectral ellipsometerindicated a refractive index n of 1.87 and optical extinctioncoefficient k of 0.23 at 193 nm.

Example 4

4.0 g of a reaction solution containing 0.8 g ofpoly2-hydroxypropyl-methacrylate resin obtained in Synthesis Example 1was mixed with 0.8 g of the compound obtained in Synthesis Example 3,0.4 g of hexamethoxymethylmelamine as a crosslinking agent and 0.04 g ofp-toluenesulfonic acid as a hardening agent and to the mixture 35 g ofethyl lactate was added as a solvent. Then, the solution was filteredthrough a micro filter made of polyethylene having a pore diameter of0.10 μm, and then, the solution was filtered through a micro filterhaving a pore diameter of 0.05 μm, to prepare an anti-reflective coatingcomposition in the state of solution. The solution was coated on asilicon wafer using a spinner and the wafer was heated at 205° C. for 1minute on a hot plate to form an anti-reflective coating (filmthickness: 0.08 μm). Measurement of the anti-reflective coating by aspectral ellipsometer indicated a refractive index n of 1.80 and opticalextinction coefficient k of 0.38 at 193 nm.

Example 5

1.6 g of the compound obtained in Synthesis Example 4 was mixed with 0.4g of hexamethoxymethylmelamine as a crosslinking agent and 0.04 g ofp-toluenesulfonic acid as a hardening agent and to the mixture 35 g ofethyl lactate was added as a solvent. Then, the solution was filteredthrough a micro filter made of polyethylene having a pore diameter of0.10 μm, and then, the solution was filtered through a micro filterhaving a pore diameter of 0.05 μm, to prepare an anti-reflective coatingcomposition in the state of solution. The solution was coated on asilicon wafer using a spinner and the wafer was heated at 205° C. for 1minute on a hot plate to form an anti-reflective coating (filmthickness: 0.08 μm). Measurement of the anti-reflective coating by aspectral ellipsometer indicated a refractive index n of 1.96 and opticalextinction coefficient k of 0.65 at 193 nm.

Comparative Example 1

10 g of a solution containing 2 g of the resin obtained in SynthesisExample 2 above was mixed with 0.53 g of hexamethoxymethyl melamine as acrosslinking agent and 0.05 g of p-toluenesulfonic acid monohydrate as ahardening agent and the mixture was dissolved in 14.3 g of ethyllactate, 1.13 g of propylene glycol monomethyl ether, and 2.61 g ofcyclohexanone as solvents to form a 9% solution. Then, the solution wasfiltered through a micro filter made of polyethylene having a porediameter of 0.10 μm, and then, the solution was filtered through a microfilter having a pore diameter of 0.05 μm, to prepare an anti-reflectivecoating forming composition. The solution was coated on a silicon waferusing a spinner and the wafer was heated at 205° C. for 1 minute on ahot plate to form an anti-reflective coating (film thickness: 0.23 μm).Measurement of the anti-reflective coating by a spectral ellipsometerindicated a refractive index n of 1.60 and optical extinctioncoefficient k of 0.47 at 193 nm.

Test Example 1

The solutions obtained in Examples 1 to 5 and Comparative Example 1 werecoated on silicon wafers by means of a spinner. The coated siliconwafers were heated at 205° C. for 1 minute on a hot plate to formanti-reflective coatings (film thickness 0.23 μm). The anti-reflectivecoatings were dipped in a solvent used for resists, for example, ethyllactate and propylene glycol monomethyl ether and as a result it wasconfirmed that they were insoluble in these solvents.

The solutions obtained in Examples 1 to 5 and Comparative Example 1 werecoated on silicon wafers by means of a spinner. The coated siliconwafers were heated at 205° C. for 1 minute on a hot plate to formanti-reflective coatings (film thickness 0.23 μm) and their filmthicknesses were measured. On each anti-reflective coating forlithography was coated a commercially available resist solution(manufactured by SUMITOMO CHEMICAL CO., LTD., trade name: PAR710, etc.)by means of a spinner. The coated wafers were heated at 130° C. for 1minute on a hot plate. After exposure of the resists to light, postexposure baking was performed at 130° C. for 1.5 minutes. Afterdeveloping the resists, the film thicknesses of the anti-reflectivecoatings were measured and as a result it was confirmed that nointermixing occurred between the anti-reflective coatings forlithography obtained in Examples 1 to 3 and Comparative Example 1 andthe resist layers.

Dry-etching was carries out for the above-obtained anti-reflectivecoatings under the same condition. Selectivity in dry-etching means thedry-etching rate of an anti-reflective coating when the dry-etching rateof the photoresist was set at 1.00.

TABLE 1 Refractive Optical extinction Selectivity index (n) coefficient(k) in dry-etching Example 1 1.76 0.11 1.64 Example 2 1.76 0.17 1.83Example 3 1.87 0.23 2.16 Example 4 1.80 0.38 1.47 Example 5 1.96 0.651.48 Comparative 1.60 0.47 0.88 Example 1

The gas composition for dry-etching was CF₄. The etching characteristicsof the anti-reflective coating obtained from the composition for forminganti-reflective coating of Example 1 were higher than those of the prioranti-reflective coating of Comparative Example 1. Particularly, it wasconfirmed from Example 3 that etching rate was increased with anincrease in the content of cyanuric acid derivative.

From the following, it is required that the dry-etching rate of ananti-reflective coating is higher than that of a photoresist: In theprocess of developing a photoresist formed on an anti-reflective coatingand then exposing an underlying substrate by dry-etching, thedry-etching of the anti-reflective coating progresses faster than thatof the photoresist, thereby decrease of the photoresist is suppressedand the anti-reflective coating is effectively removed. Therefore, thepattern on developed photoresist can be precisely transferred on thesubstrate. Consequently, the composition for forming an anti-reflectivecoating of the present invention is very effective because it providesan anti-reflective with practical reflective index and opticalextinction coefficient and for holding a high dry-etching rate. Inparticular, among the compounds of formula (1),tris(hydroxyalkyl)isocyanurate that has no functional group, such asphenyl group or alicyclic structure in its molecule is very effectivebecause it induces a high dry-etching rate.

INDUSTRIAL APPLICABILITY

The present invention provides compositions from which anti-reflectivecoatings with high dry-etching rate can be formed. The obtainedanti-reflective coatings are not only excellent in reflection reducingeffect but also able to be rapidly removed in a dry-etching process ofan underlying substrate.

The present invention can provide a composition for forming ananti-reflective coating which has a higher dry-etching rate thanresists, and a high reflection reducing effect, causes no intermixingwith a resist layer and has no diffusing material into a resist in theheating and drying process to give an anti-reflective coating with ahigh resolution and an excellent dependency on thickness of resist.Further, the composition can form an excellent resist pattern on asubstrate.

1. A composition for forming an anti-reflective coating for use in alithographic process in manufacture of a semiconductor device,comprising as a component a resin containing cyanuric acid or aderivative thereof, or a resin containing a structural unit derived fromcyanuric acid or a derivative thereof, and a crosslinking agent havingat least two crosslink forming functional groups for forming theanti-reflective coating being used in the lithographic process inmanufacture of the semiconductor device.
 2. The composition according toclaim 1, wherein the component contains cyanuric acid or a derivativethereof, represented by formula (1):

wherein R¹, R² and R³ independently of one another are a hydrogen atom,a halogen atom, a substituted or unsubstituted alkyl group having 1 to10 carbon atoms, a substituted or unsubstituted benzene derivativegroup, a substituted or unsubstituted vinyl derivative group or an epoxyderivative group.
 3. The composition according to claim 1, wherein thecomponent is a resin containing in a main chain or a side chain thestructural unit derived from the compound of formula (1), or a resincontaining in both a main chain and a side chain the structural unitderived from the compound of formula (1).
 4. The composition accordingto claim 2, wherein the compound of formula (1) istris(hydroxyalkyl)isocyanurate.
 5. The composition according to claim 3,wherein the compound of formula (1) is tris(hydroxyalkyl)isocyanurate.6. A semiconductor device, comprising: a substrate; the resin of claim 1disposed on the substrate; and a photoresist disposed on the resin,wherein the resin has a higher dry-etching rate than the photoresist.